Britons are facing confusion over trips to Canada following a U-turn on new entry rules.

Canadian authorities have backtracked on a requirement for British travellers to apply for an electronic travel authorisation (eTA) to enter the country by air after widespread problems with the online application forms.

But some individuals with eTA applications already lodged were not informed of the change, prompting fears that their airlines would not permit them to board.

British travellers face confusion over the deferral of a system requiring them to buy an electronic travel authorisation before arriving in the country by air.

Paul Osborne from Renfrew in Scotland contacted Telegraph Travel after a three-week silence from eTA-issuing authorities and no confirmation that his wife's application was being processed.

His wife applied for eTAs on January 30 for a trip to Toronto to see her aunt but was left in the dark as to whether the application was being dealt with.

“It was very frustrating. My wife was told she would not be able to get on the plane," said Mr Osborne.

“There was no indication that the application was being processed - we felt like we were in wonderland and didn’t know what was going on. There was no indication that [our application] was in a queue.”

Mrs Osborne’s eTA application was eventually successful late last week, but Mr Osborne said he hadn’t had any notice that the document was no longer a prerequisite for the trip, planned for April, and had not heard from his airline either.

"We felt like we were in wonderland and didn’t know what was going on. There was no indication that [our application] was in a queue.”

Paul Osborne, who applied for an eTA for a family visit to Canada

Travellers are required to fill out personal and health details, in a similar fashion to the Esta required for travel to the USA. The eTA is valid for five years, or until the passenger's passport expires.

The grand launch intended for March 15 has now been pushed back six months until September 30 2016.

The website has a warning notice stating that users “may experience delays” because of an “internal technical issue”.

A spokesperson for the Canadian department for Immigration, Refugees and Citizenship insisted that the scheme had not been delayed and that, "starting March 15, 2016, it will be a requirement for visa-exempt foreign nationals travelling to Canada on a temporary basis by air."

But they confirmed a "leniency period" until the autumn during which travellers would be allowed to enter Canada without an eTA. This was to help "minimize any potential travel disruptions" after feedback from "the air industry, tourism and travel sectors," they said.

Mr Osborne’s experience and those recorded by other prospective visitors suggest the problem quickly spread.

The Canadian government spokesperson insisted all airlines flying to the country, including those flying from the UK to Canada, had been informed of the "leniency period."

But there was no warning of the change on either Air Canada's or British Airway's websites and it was not clear if they were communicating with passengers about the deferral interval.

Mr Osborne said he had no contact from his airline or Canadian authorities.

Another prospective traveller wrote on TripAdvisor:

“The latest glitch is that the airlines haven't been informed so I've emailed Air Canada to let them know and am waiting for confirmation I can fly without an eTA.”

British Airways, which flies from the UK to Calgary, Vancouver, Toronto and Montreal, said passengers flying after March 15 “are expected to obtain an eTA”. But a subsequent statement added that “to avoid any potential travel disruptions they are allowing a grace period up until September 30. During this period customers without an eTA will not be prevented from travelling and providing that they are not otherwise inadmissible, will still be allowed to enter Canada.”

The UK Foreign Office advice page does not currently contain information about the deferral of the requirement to have an eTA.

Other travellers on a TripAdvisor forum said they had experienced problems submitting their eTA application and were left in the dark about the status of their request. One user wrote that she was “frustrated and disheartened” by the system. Her application had mistakenly been lodged as a work permit by Canadian authorities, instead of a travel document for a transit to a family holiday in the USA.

“I am now having to look into alternative flights that don't transit through Canada”, the user wrote.

“The most frustrating part is that I've also raised a case specific form and received no response in addition to contacting the Canadian embassy, visa processing centre and border security agency regarding this - I have been told that they ‘don't deal with eTA's’ and can't help me."

The British Foreign Office said they couldn’t confirm or deny if they had been informed of the U-turn, but said that they “would update their travel advice accordingly” once informed. “If it is a recent change it may still be going through the system”, a spokesperson said.

The Canadian visa authority home page confirms the eTA requirement is being deferred until the autumn.

But other parts of the website still say British citizens require an eTA to be allowed into Canada by air.

Its Canada travel advice page still says that Britons travelling after March 15 require an eTA.

The official Canadian immigration website also provides conflicting information about eTA requirements.

Although the home page now states that until autumn 2016 “travellers who do not have an eTA can board their flight, as long as they have appropriate travel documents,” the application process still implies that British citizens need an eTA to travel.

When Telegraph Travel tested the system this morning for British applicants– we were told that we would need an eTA for travel after March 15.

The Canadian government spokesperson said: "The majority of applicants who completed the [eTA] form found it to be easy to use. That said, like many new IT solutions, there was an adjustment period following the launch of a new system. The new eTA application system experienced periodic system issues that temporarily (usually a few hours at most) affected the ability of individuals to apply for an eTA online."